iOS: Remove a11y workaround that disables the a11y when app is resigned.

shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

@@ -862,7 +862,6 @@ - (void)dealloc {
 
 - (void)applicationBecameActive:(NSNotification*)notification {
   TRACE_EVENT0("flutter", "applicationBecameActive");
-  self.view.accessibilityElementsHidden = NO;
   if (_viewportMetrics.physical_width) {
     [self surfaceUpdated:YES];
   }
@@ -871,9 +870,6 @@ - (void)applicationBecameActive:(NSNotification*)notification {
 
 - (void)applicationWillResignActive:(NSNotification*)notification {
   TRACE_EVENT0("flutter", "applicationWillResignActive");
-  if ([FlutterViewController isUIAccessibilityIsVoiceOverRunning]) {
-    self.view.accessibilityElementsHidden = YES;
-  }
   [self goToApplicationLifecycle:@"AppLifecycleState.inactive"];
 }
 

shell/platform/darwin/ios/framework/Source/FlutterViewControllerTest.mm

@@ -932,54 +932,6 @@ - (void)testHideOverlay {
   engine.viewController = nil;
 }
 
-- (void)testHideA11yElements {
-  FlutterDartProject* project = [[FlutterDartProject alloc] init];
-  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar" project:project];
-  [engine createShell:@"" libraryURI:@"" initialRoute:nil];
-  FlutterViewController* realVC = [[FlutterViewController alloc] initWithEngine:engine
-                                                                        nibName:nil
-                                                                         bundle:nil];
-  id flutterViewControllerClassMOCK = OCMClassMock([FlutterViewController class]);
-  [[[flutterViewControllerClassMOCK stub] andReturnValue:@YES] isUIAccessibilityIsVoiceOverRunning];
-
-  XCTAssertFalse(realVC.view.accessibilityElementsHidden);
-  [[NSNotificationCenter defaultCenter]
-      postNotificationName:UIApplicationWillResignActiveNotification
-                    object:nil];
-  XCTAssertTrue(realVC.view.accessibilityElementsHidden);
-  [[NSNotificationCenter defaultCenter]
-      postNotificationName:UIApplicationDidBecomeActiveNotification
-                    object:nil];
-  XCTAssertFalse(realVC.view.accessibilityElementsHidden);
-  engine.viewController = nil;
-
-  [flutterViewControllerClassMOCK stopMocking];
-}
-
-- (void)testDontHideA11yElementsWhenVoiceOverIsOff {
-  FlutterDartProject* project = [[FlutterDartProject alloc] init];
-  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"foobar" project:project];
-  [engine createShell:@"" libraryURI:@"" initialRoute:nil];
-  FlutterViewController* realVC = [[FlutterViewController alloc] initWithEngine:engine
-                                                                        nibName:nil
-                                                                         bundle:nil];
-  id flutterViewControllerClassMOCK = OCMClassMock([FlutterViewController class]);
-  [[[flutterViewControllerClassMOCK stub] andReturnValue:@NO] isUIAccessibilityIsVoiceOverRunning];
-
-  XCTAssertFalse(realVC.view.accessibilityElementsHidden);
-  [[NSNotificationCenter defaultCenter]
-      postNotificationName:UIApplicationWillResignActiveNotification
-                    object:nil];
-  XCTAssertFalse(realVC.view.accessibilityElementsHidden);
-  [[NSNotificationCenter defaultCenter]
-      postNotificationName:UIApplicationDidBecomeActiveNotification
-                    object:nil];
-  XCTAssertFalse(realVC.view.accessibilityElementsHidden);
-  engine.viewController = nil;
-
-  [flutterViewControllerClassMOCK stopMocking];
-}
-
 - (void)testNotifyLowMemory {
   FlutterEnginePartialMock* mockEngine = [[FlutterEnginePartialMock alloc] init];
   FlutterViewController* viewController = [[FlutterViewController alloc] initWithEngine:mockEngine